FP4A/Contour 3 SW

Hello,

Our FP4A with conotour 3 recently died. Initially it would come up with "BA 0" and not respond to any button presses. After replacing the batteries we are getting "BA 00 30 : BA16", but are unable to reset the control following the procedure for this. On NSV90 we see the SF led is lit, on NPP91 we see all leds F1 through F8 being lit. We checked the NSV90 dip switches, they are correct.

In addition, I've bench tested the NSV90/NPP91 hardware and cannot find any damaged components. Battery, reset signals, PSU comparators and xtal is working, but the watchdog output on NSV90 IC3 pin 3 does not start pulsing. I think we're not able to reload SW because the keypad is not being read the way it should. Maybe the initial BA 0 error was an issue with NPP54 not reading the keypads?

I am thinking next step would be to reload the EPROM? We have blank chips and EPROM programmer available. Unfortunately we do not have backup-files.
The NPP91 chips are marked 44907-352.30(A&B) and 44205-402.02 (C). The eproms in the Contour 3 control are marked 44206-481.42(NPP54), 44206-481.82(NRP), 44206-481.11(NZP), v1.15(NPP55)

I'm grateful any guidance with this old machine.

Kind regards, Cato

a friend of me has the same machine and it seems to have a issue with the NRP card. When that one is swapped from another machine it works fine. There are 4 eeproms on the pcb w sw 44206-461.85
The 3 first ones a b c have data in them and the 4th one, D, reads empty. Is that meant to be? Ill try to get hold of the runningg card to see if that has data in the 4th chip.

Ok so it seems the memories where fine but the large IC below the D memory had a bad contact in its socket. I wonder why most of the 74 series gates are actually socketed. The other board he had most of them wered soldered in place.